Ocado said of the fire in a statement: "The incident and the measures being taken to contain it appears to have affected a proportion of the mechanical handling equipment and some of the grid.

Image:Firefighters have been working inside the huge building throughout the day. Pic: @Hants_fire

A number of customers used the company's Twitter account to complain about failed deliveries.

A standard reply blamed "operational issues", adding that it was hoped deliveries would be "back to business as usual shortly". The Andover centre is one of only four distribution centres operated by Ocado in the UK.

We are sorry to hear there has been an issue with booking a delivery today :( We have experienced some operational issues, but we expect to be back to business as usual shortly :) Thank you for your patience. - Mitch

Ocado's statement added: "Although some orders had already left the warehouse before the incident and will be delivered as normal, Andover suspended operation this morning preventing further fulfilment of orders.

"We will assess the damage this incident has caused to the Andover Customer Fulfilment Centre and will update further as appropriate."

The blaze began hours before the company revealed its full-year results which showed rising sales but deepening losses as it continued to invest in its systems.

Ocado reported a loss after tax of £44.4m for the 52 weeks to 2 December compared to £9.8m in the same period a year earlier.

Image:Ocado said it grew its UK customer base in 2018

Revenues were 12% higher at almost £1.6bn as active customer numbers passed the 700,000 mark.

The results contained no response to market speculation of tie-up talks between Ocado and Marks & Spencer but did contain news of a one-hour delivery trial in west London.

Laith Khalaf, senior analyst at Hargreaves Lansdown, said the robot technology developed by Ocado had been a key driver behind a quadrupling of its share price in two years.

He said: "It's been a transformational year for the online supermarket, though its success won't show in bottom line for several years to come.

"Indeed Ocado isn't expected to turn a profit until 2020, and is one of the most expensive shares in the Footsie, reflecting the stock market's forecast of stellar long-term growth.

"That's because Ocado has managed to sign deals with a number of international supermarkets, to help them crack the online delivery market.

"A slick mobile app and huge robotic warehouses are behind Ocado's success, know-how which can be licensed out to international partners in need of digital expertise.

"Amazon's purchase of the grocery chain Whole Foods in 2017 probably helped too, by sending shivers through the food retail sector and flushing out deals with US, French, Swedish and Canadian supermarket groups," he said.